Cardiovascular haptic handle system

ABSTRACT

Cardiac tissue motion characteristics acquired by novel cardiac sensors are analyzed and processed for the derivation of physiological indices. The indices are output to a hand held local or remote volumetric haptic display and enable an operator to obtain motion related dynamic characteristics of cardiac tissues. The ability to tactually sense the motion of cardiac tissue and the affect on such motion from inserted cardiovascular instrumentation enhances the operator&#39;s performance of procedures including the positioning and placement of implanted catheters/sensors, extraction of permanently implanted leads and delivery of cardiovascular therapies. Optimal haptic rendering is achieved by using computational techniques to reconstruct the physically and perceptually relevant aspects of acquired signals and bridge the gap between the inserted catheter and operator&#39;s hand/catheter handle.

RELATED APPLICATIONS

-   I. This application is a continuation of U.S. patent application    Ser. No. 12/836,636, filed Jul. 15, 2010 now abandoned, published as    US2010/0312129A1, which is a continuation-in-part of U.S. patent    application Ser. No. 11/686,602, filed Mar. 15, 2007 now U.S. Pat.    No. 7,963,925, which is a continuation of U.S. patent application    Ser. No. 11/584,465, filed Oct. 20, 2006 now abandoned, which is a    continuation-in-part of U.S. patent application Ser. No. 11/334,935,    filed Jan. 19, 2006 now abandoned, published as US2006/0167529A1,    which claims the benefit of U.S. Provisional Application No.    60/660,101 filed Mar. 9, 2005 and U.S. Provisional Application    60/647,102 filed Jan. 26, 2005, and-   II. this application is a continuation of U.S. patent application    Ser. No. 12/836,636, filed Jul. 15, 2010 now abandoned, published as    US2010/0312129A1, in which:    -   (a) U.S. patent application Ser. No. 12/836,636 is also a        continuation-in-part of U.S. patent application Ser. No.        12/245,058, filed Oct. 3, 2008 now abandoned, published as        US2009/0030332A1,    -   (b) U.S. patent application Ser. No. 12/836,636 is also a        continuation-in-part of U.S. patent application Ser. No.        11/848,346, filed Aug. 31, 2007 now abandoned, which is a        continuation-in-part of U.S. patent application Ser. No.        11/771,233, filed Jun. 29, 2007 now abandoned, which is a        continuation-in-part of U.S. patent application Ser. No.        11/746,752, filed May 10, 2007 now abandoned,    -   (c) U.S. patent application Ser. No. 12/836,636 is also a        continuation-in-part of U.S. patent application Ser. No.        11/848,346, filed Aug. 31, 2007 now abandoned, which is also a        continuation-in-part of U.S. patent application Ser. No.        11/746,752, filed May 10, 2007 now abandoned,    -   (d) U.S. patent application Ser. No. 12/836,636 is also a        continuation-in-part of U.S. patent application Ser. No.        11/848,346, filed Aug. 31, 2007 now abandoned, which is also a        divisional of U.S. patent application Ser. No. 11/686,602 now        U.S. Pat. No. 7,963,925, which is a continuation of U.S. patent        application Ser. No. 11/584,465, filed Oct. 20, 2006 now        abandoned,        each of which is a continuation-in-part of U.S. patent        application Ser. No. 11/334,935, filed Jan. 19, 2006 now        abandoned, published as US2006/0167529A1, which claims the        benefit of U.S. Provisional Application No. 60/660,101 filed        Mar. 9, 2005 and U.S. Provisional Application 60/647,102 filed        Jan. 26, 2005, and-   III. this application is a continuation of U.S. patent application    Ser. No. 12/836,636, filed Jul. 15, 2010 now abandoned, published as    US2010/0312129A1, which is a continuation-in-part of U.S. patent    application Ser. No. 11/848,346, filed Aug. 31, 2007 now abandoned,    which is a continuation-in-part of U.S. patent application Ser. No.    11/771,233, filed Jun. 29, 2007 now abandoned, which is a    continuation-in-part of U.S. patent application Ser. No. 11/746,752,    filed May 10, 2007 now abandoned, which also claims the benefit of    U.S. Provisional Application No. 60/885,820, filed Nov. 1, 2006, and-   IV. this application is a continuation of U.S. patent application    Ser. No. 12/836,636, filed Jul. 15, 2010 now abandoned, published as    US2010/0312129A1, which is a continuation-in-part of U.S. patent    application Ser. No. 11/848,346, filed Aug. 31, 2007 now abandoned,    which is also a continuation-in-part of U.S. patent application Ser.    No. 11/746,752 filed May 10, 2007 now abandoned, which also claims    the benefit of U.S. Provisional Application No. 60/885,820, filed    Nov. 1, 2006, and-   V. this application is a continuation of U.S. patent application    Ser. No. 12/836,636, filed Jul. 15, 2010 now abandoned, published as    US2010/0312129A1, which claims the benefit of U.S. Provisional    Application No. 61/270,924, filed Jul. 15, 2009 and U.S. Provisional    Application 61/341,129, filed Mar. 7, 2010 and U.S. Provisional    Application 61/369,575, filed May 29, 2010, all of which are    incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a hand-held haptic control system with tactileforce feedback that acquires dynamic cardiac mechanical data as togenerate multidimensional tactile simulations of the intra-cardiacenvironment in real time via a hand held Cardiovascular Haptic Handle(CHH) providing physiologic information in form of a tactualrepresentation in real time. The CHH system eliminates the effects of acatheter's dampening properties, the attenuation effects of interveningtissues and the affect of the operator's gross motions on an insertedcatheter's ability to provide the operator with a tactual representationof cardiac tissue motion and the effects of catheter—tissue contact.Though the system can function in conjunction with visual displays, itcan provide mechanical and anatomical information with a hapticrepresentation and replace the need for a visual display.

2. Description of Prior Art

Medical catheters and sheaths are generally tubular shaped and of asufficiently small diameter to be inserted into a patient's body througha small incision, puncture or a natural opening. Such catheters can beused to deploy inner catheters, cardiac leads, electrodes, delivercontrast (e.g. radiopaque dye) or ablative energy in form ofelectromagnetic energy (e.g. current, radiofrequency energy, light) andare flexible as described by Brock et al in U.S. patent application Ser.No. 12/023,685. One example is lead extraction systems that implement anexcimer laser. Unfortunately, as conventionally designed catheterscourse through a patient's tissues and vasculature the operator looseshis or her ability to appreciate the forces restricting catheter motionsecondary to attenuation and frictional effects and due to the compliantnature of the inserted catheters.

Catheters for performing coronary/peripheral angiography and vascularinterventions are well understood by those experienced in the art. Morerecently, catheters have been designed for engaging the coronary sinusand positioning pacing leads about the left ventricle for cardiacresynchronization therapy which is often difficult and time consumingrequiring large amounts of radiation exposure. These catheters can alsodissect vessels and intracardiac structures leading to cardiovascularcollapse. Unfortunately, the operator can not appreciate the dynamiccharacteristics of contacted tissue or the forces along the distalportion of these catheters and mainly relies on radiographic imagesduring catheter manipulation (e.g. fluoroscopy). These images are twodimensional and necessitate exposure to radiation. Tactile feedbacksystems incorporated into the design of these catheters would reducecomplication rates, expedite procedures and minimize radiation exposureto the operator and patient alike and most importantly, provide insightsinto cardiac tissue mechanics.

Electrograms have been demonstrated to be poor predictors ofelectrode-tissue contact for ablation procedures (see Ikeda A. et al.Electrogram Parameters (Injury current, amplitude, dV/dt) and Impedanceare poor predictors of electrode-tissue contact force (seeElectrode-Tissue Contact Force for Radiofrequency Ablation. Heart RhythmSociety, May 2008, Abstract 4570, P05-41).

The phasic nature of the contracting heart and respirations affectslesion characteristics from ablative energy because of intermittentcontact and variations in applied force at the electrode-tissueinterface (Shah D C et al. Area under the real-time contact force curve(force-time integral) predicts radiofrequency lesion size in an in vitrocontractile model. J Cardiovac Electrophysiol, 2010, pp 1-6). Real-timetactile force-feedback via the Haptic Handle will ensure safe andeffective delivery of therapy without a need for the operator to lookaway from the visual/fluoroscopic image of the heart and obviates a needto look at a separate force graphic display during critical time frames.The CHH will complement technologies that provide force information(available e.g. from Endosense Tacticath of Geneva Switzerland, HansenMedical of Mountainview, Calif.) and improve outcome with minimaladditional expense, obviate the need for expensive navigational systemsand reduce fluoroscopic exposure. It will also enable the operator tomore deeply sedate patients during their procedures as verbal feedbackof discomfort during delivery of ablation energy will not be necessary.

A variety of devices can be used as a haptic display including but notlimited to programmable keyboards, augmented mice, trackballs,joysticks, multi-dimensional point and probe-based interactions,exoskeletons, vibro-tactor arrays, gloves, magnetic levitation, andisometric devices (Burdea, G C. Force and Touch Feedback for VirtualReality. New York: Wiley Interscience, 1996). These systems are used forvirtual simulations or for evaluation of non-moving, static structures.There remains a need for haptic representation of moving biologicaltissue.

Mottola et al (U.S. Pat. No. 6,059,759) describes an infusion cathetersystem with an occluding wire that generates vibrations when the wireprotrudes along a ridge notifying the operator that the wire extendsbeyond the confines of the inserted catheter. This does not provide theoperator with information about the mechanics of cardiacmotion/deformation or the effect of the catheter on cardiac mechanics.

Wallace D, et al has developed a robotic catheter manipulator thatincludes at least one force sensor for measuring the force applied tothe working catheter by a ditherer during operation (U.S. patentapplications publications nos. 20070233044, 20070197939). Forcemeasurements are estimated and displayed to the physician via a monitoror display. In Wallace's application, an alarm signal can notify theoperator that too high a force is applied via an audio, video or hapticsignal, though there is no tactile appreciation or simulation of tissuemechanics/motion present at the distal portion of the catheter. Such adesign is found in ablation catheters manufactured by Hansen MedicalInc., Mountainview, Calif.

No current technology provides the operator with a dynamic mechanicalsimulation of the heart, surrounding vasculature or the effect of aninserted instrument on cardiovascular tissue deformation and motion. Theaddition of tactile force feedback to commonly used cathetermanipulators will provide an operator with a unique ability to sense thephysical action of an inserted catheter on a rapidly moving biologicalstructure while controlling fine motion of the catheter's distal aspectand acquiring physiologically significant data about cardiac function.

References—to be Listed Separately in an IDS.

SUMMARY OF THE INVENTION

It is clear to the inventor that there is a great need in the art forsystems that provide surgeons using catheters with various tactileinformation during a procedure, especially cardiac diagnostic procedureswhere normal and pathological physiologic information can be acquired asto assist in delivery of appropriate therapies. The present inventionpertains to a system in which catheters or external sensing systems areprovided with haptic rendering of cardiac tissue motion characteristics.

Though haptic rendering through any means (including teleoperation) iswithin the scope and spirit of this invention, the preferred mode forreal-time rendering is via a volumetric Haptic Handle that most closelysimulates handles that are part of conventionally used dexterousintravascular catheters familiar to cardiologists, surgeons andelectrophysiologists who currently perform invasive cardiac proceduresand lead extraction procedures. Transducers provide passive simulationof cardiac tissue motion and also can be coupled with active elementsthat direct the motion and location of multiple segments along aninserted catheter.

Various types of motors can be provided to implement rendering tactileforce and vibrotactile feedback including but not limited tolongitudinal/linear, rotary, ultrasonic, piezoelectric, normally locked,normally free motors, etc. as known by those experienced in the art(e.g. U.S. Pat. Nos. 3,184,842, 4,019,073, 4,210,837).

Miniaturized sensors such as piezoelectric sensors or accelerometers areused to acquire intra-cardiac data representative of myocardial wallmotion. The sensors produce signals in response to the motion of theventricular wall locations that relate to mechanical tissuecharacteristics during the cardiac cycle but do not provide a tactilesimulation of dynamic cardiac properties in real time.

Other types of sensors are used that may be based on electromagneticsystems to gather information about tissue mechanics. For example, thesensors described by Aeby and Leo to sense tri-axial forces incorporateoptical fibers to generate variable intensities of light as a functionof deformation (see U.S. patent application publication number20080009759). These systems provide the operator with measurements ofcontact force at the catheter's distal end and three dimensionalanatomic localization data. Externally located magnetic andelectromagnetic fields found in three dimensional navigational systemsare known that provide cardiac anatomic information (e.g EnSite NavXsystem (St. Jude Medical, Austin, Tex.) but do not communicate dynamiccardiac tissue mechanical information to the operator nor providetactile feedback.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram for handling information in accordance withthis invention.

FIG. 2 illustrates analogous signals of cardiac motion obtained withintra-cardiac sensors (middle) and tissue Doppler echocardiography(top—longitudinal motion, bottom—rotational motion). Sensors deployed indifferent locations and with different orientations along an insertedcatheter will gather motion information along different vectors.

FIG. 3 depicts tissue Doppler motion, TDI, bottom and current waveformfrom a piezoelectric sensor (top) and voltage waveform (middle) frommotion detected within the left atrial appendage, LAA, in a patient withatrial flutter.

FIG. 4 a is an electron micrograph of helical nanosprings

FIG. 4 b is a depiction of multiple nanosensors deployed in threedimensions in the distal portion of an intra-cardiac catheter.

FIG. 4 c left is an electron micrograph of an individual ZnO nanowireand 4 c—right illustrates how nanowires are radially positioned about aKevlar fiber core mechanically reinforced with layers of TEOS (see textfor details) create a nanogenerators (NG).

FIG. 5 force information as a function of time can be tactuallycommunicated directly as displacement in the haptic handle such that theforce is linearly converted to a tactual metric of displacement with aforce proportionate to the sensor force. The relationship may be linearbut plateaus at force, F*. The plateau force is dependent on a number offactors including the mechanical properties of the sensor.

FIG. 6 shows how a maximal frequency, f max, is reached while the actualfrequency of deformation of the sensor (abscissa) increases but is notaccurately represented in the haptic display (ordinate).

FIG. 7 a depicts nodes A and B that are present in a CHH virtualcatheter design that shares the properties/construction features of thedistal end. Cardiac tissue motion characteristics are acquired viainternal and/or external sensors at specific nodes along the insertedcatheter/instrument and communicated at multiple joints or nodes (nodesA and B in Figure) along the CHH (virtual coupling). These nodes arepresent in a simulated version of the catheter which acts as the hapticdisplay.

FIG. 7 b illustrates multiple high frequency rotary motors and a lowfrequency longitudinal motor (stator) within a Cardiovascular HapticHandle, CHH.

FIG. 7 c illustrates an alternative embodiment for a CardiovascularHaptic Handle.

FIG. 8 a illustrates how the fine, high frequency motion of thefibrillating LAA generates a proportionate amount of current as afunction of time which is translated into a similar quality motion inthe haptic display.

FIG. 8 b is a transesophageal image illustrating the proximity of theleft upper pulmonary vein (PV) to the LAA and associated structures.

FIG. 9 is ultrasonic pulsed wave Doppler signals detected as thecatheter moves from a fibrillating appendage toward the pulmonary veinand illustrates how the level ramps from the effect's magnitude to afade level over a fade time corresponding to the intra-cardiac movementimposed onto the catheter's distal portion at varying locations.

FIG. 10 once within the pulmonary vein, the fibrillatory sensation (top)will fade out and an intermittent biphasic constant motion will beappreciated secondary to pulmonary venous inflow (bottom). Hapticrendering will be very important as to maintain passivity and optimizethis transition.

FIG. 11 is a block diagram/representation of the workings of theinvention. Sensor PzS sends current signals, I, via conductor(s) (e.g.CNTC) that are A/D converted in processor 10. High/Low pass filteringseparates tactile data and delivers varying frequency information todifferent portions of the Cardiovascular Haptic Handle, CHH. Externalsensing systems provide a continuous frame of reference for insertedsensor(s)/catheter and CHH in space-time. In this example, 10, isseparate from the CHH reducing its bulk and the signals are transmittedvia wiring, though wireless communication is within the scope and spiritof the invention.

FIG. 12 one or more linear displacement motors, LF, which moves to andfro, in one degree of freedom (1-DOF) coaxial to the inserted catheter,is driven by the low frequency component of the current signal, I. Oneor more high frequency motors, HF, imparts high frequency informationfor reproduction of vibrotactile information to the HH (up and downarrows). A knob or collar mechanism at the distal CHH providestemperature or texture information and serves to deflect or maneuver oneor more portions of the inserted catheter.’

FIG. 13 the network model of haptic simulation.

FIG. 14 the haptic interface

FIG. 15 zero order haptic display

FIG. 16 top left is an anatomic rendition of how a catheter or needletraverses the interatrial septum in a left anterior oblique (LAO) view.The bottom demonstrates pressure recordings during this manipulation andthe effect of catheter fling.

FIG. 17 shows a somewhat simplified view of a haptic handle systemconstructed in accordance with this invention;

FIG. 18 shows a block diagram for the system of FIG. 17.

FIG. 19 shows an alternate embodiment in which a local catheter andhandle and sensors are monitored, and optionally, operated by anoperator at a remote location using a simulated haptic catheter.

FIG. 20 shows an alternate embodiment descriptive of a virtual catheter.

DETAILED DESCRIPTION OF THE INVENTION

Data Acquisition: Motion Sensors

In one mode of this invention, temporary or permanently implantedcardiovascular instrumentation (e.g. cardiac catheters or implantedpacemaker/defibrillator leads, respectively) is equipped withtransducers that acquire sensor signals from within the cardiac tissuesand surrounding vasculature. By way of example, a piezoelectric sensoracquires information related to the motion of the contacted cardiactissues and flow characteristics of intra-cardiac blood (e.g.turbulence, laminarity). The motion and/or deformation of the sensor aredirectly proportionate to that of the neighboring tissues or fluid flow.The amount of piezoelectric voltage generated will bear a relationship(i.e. linear, exponential) to sensor motion/deformation. Physiologicindices that can be derived from these measurements include but are notlimited degree of displacement, torque, frequency of motion (can bealong specific vectors), anatomic localization, sensor orientation,characteristics of blood flow, force information (also described in theinventor's co-pending patent application Ser. No. 12/245,058,incorporated herein by reference). These indices are applied to providea haptic control system as a means for navigating about the vasculatureand heart, performing therapeutic procedures and collecting novelphysiologic information.

In one mode of the invention, piezoelectric sensors (e.g. deformation oracoustic sensor) detect properties of tissue displacement including thenatural motion/deformation of the vasculature and cardiac structures,and the effect of catheter manipulation and/or displacement caused by aninserted catheter. Such sensors can be constructed of conventionalpiezoelectric material such as PZT (lead, zirconate, titanate) or othermaterial/composite. They can be located in one or more locations alongthe inserted instrument. For catheters used for ablation of arrhythmia,the location is such that interference with the sensor secondary toablative energy does not occur and sensor integrity is not affected.

FIG. 1 shows a block diagram for handling information in accordance withthis invention; sensors (e.g piezoelectric) detect multidimensionalmotion. Sensors can be conventional piezoelectric, PzS, or nanosensors,PzN, constructed using nanotechnology. Voltage output by the PzS isproportionate to sensor motion/deformation. The resulting electricalsignal, i, is provided through a conductor (conventional ornanoconductors) can be either amplified at 5 and/or input into acontroller/processor, 10, that delivers waveforms, (for example, currentwaveforms I), to a Haptic Handle, HH, which simulates cardiac tissuemotion and the affect of omni-directional catheter motion anddeformation on such tissue motion to the operator. The controller ispreferably capable of high level haptic rendering as described in detailbelow. The controller/processor, 10, has bidirectional communicationwith processing centers 400 (peripherally located) and 1000 (centrallylocated), as well as, conventional diagnostic imaging equipment, 700, asdescribed in the parent application. In one embodiment, 10, serves toperform haptic rendering to sensed signals and deliver commands to theCHH and from the CHH to the inserted instrument(s).

Acquisition of motion information using piezoelectric sensors andpiezoelectric nanosensors (also described in inventor's co-pendingpatent application Ser. No. 12/245,058 incorporated herein by reference)enables high fidelity reproduction of sensed signals in the CHH. In oneembodiment of the invention, the analog data acquired by the sensor isin form of an electrical signal corresponding to the motion/deformationof PzS. This information includes one or more characteristics of themotion/deformation of PzS, such as frequency, vector and degree ofdisplacement. Sensors that can be used for this purpose include sensorsmade of a piezoelectric material, accelerometers, microsonometers andother similar sensors known to persons skilled in the art. Alternativelyor additionally, the input data can be acquired by an external orextrinsic means (EXT in FIG. 1) as discussed more fully below.

Referring to FIG. 2—middle, we see a current time graph illustrative oflead or catheter motion at the level of the atria-ventricular valvularannulus (along the plane of the coronary sinus) detected by an LV leador coronary sinus catheter-based accelerometer(s). The lead has PzSincorporated within its structure. Optimally, the lead/catheter remainisodiametric and in a preferred mode of the invention, PzS isconstructed with nanotechnology (e.g. carbon nanotube transducers),though other sensors can be used as well, as discussed. On the bottom ofFIG. 2 is a rotational displacement time graph depicting leftventricular torsion as determined by echocardiographic speckle trackingor other imaging technique. On top is a myocardial tissue velocity timegraph (detected with ultrasonic tissue Doppler imaging). One heart beatis depicted. Current peaks (middle) are noted at times of maximalrotational velocity and displacement during isovolumic contraction (IVC)and isovolumic relaxation (IVR). Less current flow is noted during thesystolic ejection phase and diastolic time frames (E=passive filling andA=active filling). Sensor technology, signal processing as detailedherein and haptic rendering are required in order for multiple cardiacmotion characteristics (e.g. secondary to LV rotation and atrialflutter) to be tactually appreciated simultaneously (See Schecter et al.The Effects of Atrial Flutter on Left Ventricular Rotation: A TissueDoppler Study. Heart Rhythm Society 2005; 2(1S): S134).

FIG. 3 illustrates how the voltage generated at the level of the sensor,V, and current, I, conducted to 5 and 10 are proportionate to the degreeof displacement of the PzS. Ultrasonic tissue Doppler imaging (TDI)measurements of displacement correlate with V and I for one cycle ofatrial flutter sensed with PzS (intrinsically) and extrinsically withechocardiography equipment. In FIG. 3, one flutter cycle lastingapproximately 200 milliseconds (double arrows along abscissa) isdepicted. Extrinsic sensing with ultrasound serves to calibrate novelintrinsic sensors and help define the physiological significance of thenewly acquired tactual metric of motion as described in the inventor'sco-pending patent application Ser. No. 11/584,465, incorporated hereinfor reference.

The implanted sensors are preferably made using microfabricationtechniques to will facilitate the system's ability to reproduce vectorof motion, such that the haptic display can generate a tactualrepresentation of more than one type or vector of motion in more thanone format (e.g. rotational and longitudinal velocity, acceleration,displacement). Such motion is detected by one or more sensors and can besimultaneously or independently simulated in the Haptic Handle dependingon operator preference. Devices, including self-ampifyingnano-generators can be used for this purpose as are disclosed by Qin Y,Wang X, Wang Z L. Microfibre-nanowire hybrid structure for energyscavenging. Nature. Vol 451, Feb. 14, 2008. 809-813.

The nanosprings and nanogenerators illustrated in FIGS. 4 a and 4 c,respectively, provide a more accurate signal than conventionalaccelerometers, and generate a relatively large amount of currentrelative to the degree of deformation improving signal to noise ratioalso described in inventor's co-pending patent application Ser. No.12/245,058 incorporated herein by reference.

Integration and differentiation can be performed on the acquired dataand velocity, acceleration and/or displacement is presented within theCHH based on the preference of the operator. For the purposes ofclarity, a one degree of freedom (1-DOF) tactual displacement metric isdescribed, though velocity and acceleration properties can be preservedin the final haptic representation as well. If preferred, the effect ofthe tissue motion upon the catheter, as well as, the effect of otherforces (e.g. generated by the operator) on the catheter's motion can beappreciated at the haptic end or subtracted from the final tactualrepresentation. Preferably, multiple sensors and sensor types arepositioned at specific locations as to gather specific motioncharacteristics (at varying frequencies) along the inserted instrumentin three dimensions (FIG. 4 b). The most distally located sensors willacquire data from contacted tissue while more proximally located sensorswill acquire data from catheter motion (e.g. catheter fling) that can besubtracted from the final tactual representation.

When sensors are arranged in three dimensions (FIG. 4 c), threedimensional recreation of catheter motion will be possible. Extrinsicnavigation systems (e.g. magnetic, impedance-based) can be used todetermine the proper frame of reference so that the haptic display iscorrectly oriented and accurately reproduces the vector of motion inthree dimensional space in real time relative to the inserted catheter'sand patient's position.

In another embodiment, micromechanical sensor arrays composed ofpiezoelectric MEMS resonators (MMR in FIG. 1) are used for dataacquisition and data transmission occurs wirelessly at gigahertzfrequencies (as described by Nguyen, CTC, IEEE Spectrum December 2009).Thus in this embodiment, data is wirelessly transmitted at highfrequency to a processor that detects this specific bandwidth andtranslates the acquired signal to a metric that is tactuallycommunicated in the Haptic Handle.

Regardless of the type of sensor employed the system is capable ofextracting and reproducing a wide spectrum of tactile sensations frommoving tissue including but not limited to; periodic vibrations (e.g.LAA fibrillating), texture effects (chordae tendinae, LAA ruggae),sensations of enclosure (e.g. intracavitary, within pulmonary vein,coronary sinus), saturation, stiffness (e.g. free wall), thickness (e.g.interatrial septum), spring effect, deadband, inertia, damper effects,constant force, ramp force and friction (e.g. intravascular), simulationof blood flow (laminar and turbulent).

Data Acquisition: Force Sensors

The CHH is compatible with force or pressure sensor technology and dataacquisition can be made with force/pressure sensors instead of, or inaddition to, motion sensors. Force sensors can be in any form includingbut not limited to fiber optic sensor for resolving the magnitude anddirection of force vectors wherein changes in light intensity and/orwavelength of the light transmitted through the an optical elementchanges as a result of regional strain. Force sensors of this kind aredescribed in as described in Aeby and Leo's patent applicationpublication 20090177095. Acquisition of needed data with pressuresensors can be implemented as well. Force measurements are translatedinto motion information (e.g. admittance haptic display) and tactuallyrepresented in more than one way. By way of example, force informationas a function of time can be tactually communicated directly asdisplacement in the haptic handle such that the force is linearlyconverted to a tactual metric of displacement (FIG. 5). A HapticInterface of the admittance type is used to perform this task in oneembodiment (see below). When peak force is detected, the handle willreach its peak linear displacement.

In one mode, the processor, 10, converts a force metric to adisplacement metric. Assuming a constant sensor mass (Ms) we deriveacceleration of the sensor (a.sub.$). Thus, sensor force,Fs,=Ms*a.sub.s. Double integration of a.sub.s will derive displacement,mm.

The Haptic Handle can then displace in three dimensions according tomultidimensional force sensor data acquired. Force sensors are morelimited in providing the operator with high frequency information thanpiezoelectric sensors. Referring to FIG. 6, we see a maximal frequency,f max, where the actual frequency of deformation of the sensor(abscissa) increases but is not accurately represented in the hapticdisplay (ordinate) and vibrotactile simulation is suboptimal.Piezoelectric sensors more accurately acquire higher frequencyinformation. In one embodiment, force sensor technology is implementedfor representation of gross motion in three dimensions (e.g. lowfrequency component of hybrid Haptic Handle) and piezoelectric sensorstemporally provide motion characteristics in fine detail (e.g. highfrequency vibrotactile component of hybrid Haptic Handle). Thus, in apreferred embodiment, a combination of sensors input data to processor,10, for haptic rendering and optimal coupling. Comparison of analogousdata collected with differing intrinsic sensor technologies along withdata collected with extrinsic modalities will enable the identificationof optimal sensor applications for the creation of the most passivesystem (e.g. via open connectivity/wireless communication) as describedin the inventor's co-pending patent application Ser. No. 11/334,935,incorporated herein for reference.

Data Processing: Extrinsic Navigational Systems

When extrinsic modalities such as navigational systems are used for dataacquisition, the transmitted data consists of the three dimensionallocation of the distal segment(s), (EXT in FIG. 1). Data transmissioncan occur between the extrinsic system either wirelessly or viaconductor(s) and the location information is input for processing intoprocessor, 10, and converted to motion information so that the data isthe presented tactually to the operator based on real time anatomiclocation of one or more portions of the inserted catheter's/instrument'sdistal end at discrete points in time. Haptic rendering optimizes systemtransparency, and provides for fluid motion even when a discrete timecontroller is used for data acquisition (e.g. interpolation). This isdiscussed in more detail below. An example of a haptic display in thiscapacity is one that acquires location data and outputs force (impedancedisplay—see below).

Data Processing: Sensor Output

The final sensor data or input data is representative of dynamiccardiovascular tissue motion data combined or not combined with theeffect of interactive forces between one or more insertedcatheters/instruments on contacted tissue and surrounding fluid. Inputdata is input to a processor/controller (10) that, in one embodiment,compares the resultant intrinsically acquired motion data with analogousextrinsically acquired data from conventional extra-cardiac imagingmodalities (ultrasound, radiation, magnetic, electromagnetic, impedance,electric) such as 3D navigational systems for derivation of a tactualmetric that is standardized and calibrated in form of a novel tactilephysiologic metric. The processor/controller then outputs the data inreal time as tactual simulation of acquired data (e.g. displacement) asis or as a time derivative to the operator via the haptic interface.Displacement, velocity and acceleration/force information at theproximal haptic handle closely simulate the same physical motioncharacteristics at the distal sensor end in real time providing the userwith a good feeling transparent appreciation of intracardiac motioncharacteristics.

In order to optimize signal fidelity, processor 10 providesamplification and filtering of piezoelectric generated current signals.This can also be done at any point within the system (e.g. distal,central or proximal locations). Processing and amplification that occursclosest to the sensor may optimize signal fidelity but suffers from thedrawback of increasing the size and bulk of the insertedinstrument/catheter system. In one embodiment, implementation ofnanogenerators composed of radially oriented ZnO nanowires, NG, as theactive sensor(s) satisfies both the need for a higher output signal andfor motion data acquisition (FIG. 4 c). Microfabrication techniquesprovide the necessary miniaturization (Qin Y, Wang X, Wang Z L.Microfibre-nanowire hybrid structure for energy scavenging. Nature. Vol451, Feb. 14, 2008. 809-813). Use of external sensors (EXT) wouldcircumvent need for signal amplification.

Haptic Handle: Constructs

Real-time cardiac tissue motion/deformation data acquired by one or moresensors in contact with the heart and surrounding structures iscommunicated to the clinician via a tactile force feedback system withinthe Haptic Handle. In a simplified embodiment amplifier, 5, is used todeliver signals related to internal characteristics being sensed by thesensor to drive one or more elements within the Haptic Handle, HH(FIG. 1) thereby providing a respective tactile rendering of thecorresponding internal characteristics. HH can be contained withinconventional handles (e.g. U.S. Pat. No. 6,780,183) used for positioningpacemaker leads, catheters, or intravascular delivery/extractionsystems, integrated into ablation catheter systems and the like. Theintensity of the tactile feedback is adjustable as some operators maydesire a more subtle sensation than other operators especially early onin the learning curve. In a preferred embodiment, specific frequencyranges and haptic characteristics are displayed at different positionsand with differing methods along the CHH.

Via the Haptic Handle, the operator will be able to detect when thecatheter tip is intra-cavitary (sense of enclosure), juxtaposed to theIAS (thickness, stiffness, spring), within the LAA (periodic, texture),affected by blood flow at coronary sinus os (intermittent constantforce), LA free wall (stiffness, spring, dampen), or near the mitralvalve apparatus (vibration, constant force secondary to transmitralblood flow) even with cardiac cycle dependent changes in anatomicstructure.

In one embodiment, torsional/rotational data is acquired with multiplesensors positioned about an inserted instrument/catheter and issimulated with a virtual catheter design. By way of example, amulti-electrode coronary sinus catheter can extract motion informationabout the basal portion of the heart. This location is ideal asphysiologically relevant basal left ventricular rotational informationcan be acquired. In one mode of the invention, the data is communicatedto the operator with a simulated version of the inserted catheter thatis held with both hands (virtual catheter). Distal and proximal tissuerotational data is transmitted separately to both hands such that onehand palpates the amplitude and vector of tissue motion along theproximal portion of the catheter and the other from the distal portion.In one embodiment, a virtual catheter can be held and motioninformation/force along the length of the inserted catheter is palpatedby the operator giving a real-time feel of how the distal end is movingat varying pivot points, joints or nodes (FIG. 7 a). The action of theoperator on the virtual catheter directs the motion of the insertedinstrument (virtual coupling) and vice versa.

Haptic Handle: Display Range

The relative dimensions of the cardiac/vascular compartments (CVC) andoperating range of the haptic display (HD) can be scaled 1:1 orotherwise (e.g. CVC>HD; CVC<HD). In this fashion, the operator canmodify his or her virtual experience/space and be able to continuouslyappreciate the full range of multi-dimensional motion without systeminstability. By way of example, maneuvering about a large space (e.g. a7 cm diameter atrium or between right and left atria) will require ascale downed haptic display range (HD<CVC) as to enable the controllerto be implemented comfortably and occupy a reasonable operating volume.When fine motion is required within a confined anatomic space (e.g.about the pulmonary veins, during opposition to cardiac tissue duringablation), an up-scaled haptic display range will be appropriate(HD>CVC). Thus, the operator can reset the haptic display range asneeded. Post-processing in processor 10, can be used in order to adjustall the transmitted data (e.g. displacement, velocity, acceleration)once modifications of haptic display range are programmed.

Haptic Handle: Vibratory Tactile Feedback System

In one mode of this invention, the handle accommodates one or moretactile elements in the catheter handle. These elements provide tactilesensations to the hand of the operator. These tactile sensations may beproduced by causing the elements to vibrate and/or causing them to bedisplaced either linearly or rotationally. The vibration of the tactileelements can be accomplished by using for example one or more actuatorssuch as motors rotating weights that are offset from the center ofrotation of the motor, though, other tactile/force feedback mechanismscan be utilized to provide varying tactile sensations that can besimultaneously sensed. The vibrations are true reproductions of cardiactissue vibrations/motion and describe physiologically relevantinformation to the operator rather than just a warning vibratory signal.

In one mode of the invention, the high frequency motion information iscommunicated to the operator using more than one haptic display in formof sonomicrometers or speakers that vibrate with the same frequency anddisplacement as the signals generated from one or more anatomic portionsof the heart. The haptic display(s) are positioned about the operativefield as to provide the operator with a spatial representation of thelocation of the inserted sensors in real time. In one embodiment, thefrequency range is transposed to be within the audible range of humanhearing.

Preferably, simulation of intra-cardiac motion is provided by severaltactile elements (driven by individual motors with unbalanced weights asrequired, or other similar actuators) and housed in the CHH. Theshaft(s) of one or more motors positioned with varying directions (e.g.x, y, z axes). Each actuator can receive and reproduce motioncharacteristics with differing bandwidths and from differing localesalong the inserted catheter (e.g. within the respective cardiac chamber,vessel) along three dimensions. By way of example and in one embodiment,the CHH body provides high frequency tactile simulations, the body ofthe CHH. The shaft reciprocates in a longitudinal direction simulatinglow frequency cardiac contractile motion. A knob, collar, or otherdistally located controller at the CNN's distal end (such as Temp-Textknob 204 a in FIG. 12) simulates intermediate frequency motion fortexture and temperature sensing. Texture characteristics can besimulated using haptic rendering techniques such as deliveringvariations in frequency and high frequency displacement amplitude. Thedistal portion of the inserted catheter has a temperature sensor asknown by those experienced in the art understand. This temperaturesensor delivers readings to controller 10 which then directs Temp-Textknob (204 a in FIG. 12) to vibrate at a proportionate frequency and/oramplitude that is indicative varying levels of heat (psychophysicalhaptic rendering). In one embodiment, the distally located knob orcontroller is also used to deflect, torque or move one or more portionsof the inserted catheter as is well known in the art.

Referring to FIG. 7 b we see six high frequency motors HF (or othersimilar actuators) responsive to high frequency motion sensed in thecatheter that provide physiologically relevant vibrotactile motion, acentrally located, low frequency (LF) motor or other actuator responsiveto low frequency motion, and a shaft for 1 DOF simulation of cardiactissue motion that is reproduced in a longitudinal plane. The shaft actsas an actuator to activate a respective tactile element in the handle.As previously described, the tactile element can be a knob, collar orother similar element(s) on the handle. Some existing catheters areequipped with knobs and/or collars and/or triggers used for themanipulation of the catheter (including its tip). In the presentinvention, the knob or collar etc is coupled to a respective actuator sothat they can serve dual functions of manipulating the catheter andproviding tactile sensations as discussed. The shaft is stationaryrelative to the other portions of the handle and in one embodiment itsmotion is the same as that of the catheter itself (FIG. 7 b).Alternatively, longitudinal motion is independent of the catheter andthe operator holds a stationary handle (stator or shaft) and a portionof the handle (haptic portion) acts at the tactile element and providesa 1-DOF motion to and fro and can be palpated as to reproduce andprovide an appreciation of the cardiac tissue motion at the distal endof the inserted catheter (FIG. 7 c).

Alternatively, a haptic portion can be in any shape or form and beconstructed of any material such as silicon or rubber. It can be part ofa knob, collar or ring along any portion of the handle and used todeflect, torque, move one or more portions of the distally locatedcatheter/instrument.

The fine, high frequency motion of the fibrillating left atrialappendage (LAA), illustrated in FIG. 8 a, is translated into a similarquality motion in the haptic handle alerting the operator that thecatheter is in a location putting the patient at risk for stroke. When asensor is within the left atrial chamber, a vibratory sensation isappreciated once the catheter is within the LAA during atrialfibrillation. See FIG. 8 b for anatomic detail obtained from a twodimensional ultrasonic transesophageal view. This will have variableamplitude, vector and frequency such as the high frequency periodicmovement associated with atrial fibrillation (200-500 per minute). Thismovement will have an envelope with changes in level, gain, magnituderelative to atrial appendage motion and the current generated by one ormore distally located sensors (LAA current in FIG. 8 a). An attack andfade portion ramps from the attack level to the effect's overallmagnitude over the attack time. As the catheter moves from afibrillating appendage toward the pulmonary vein the level ramps fromthe effect's magnitude to a fade level over a fade time corresponding tothe intra-cardiac movement imposed onto the catheter's distal portion atvarying locations as a function of time. Thus, as the catheter tip movestoward a pulmonary vein (FIG. 9), the vibratory amplitude will dampen.The periodic waveform can be shaped (e.g. sinusoidal, triangular,sawtooth) relative to the changes in PzN current as a function of time(FIG. 8 a). Dynamic changes in spacing and bump width simulate thetexture of contacted tissues (psychophysical haptic rendering discussedbelow). In a preferred embodiment, the higher frequency motion istactually simulated along the body and/or at the distal end of the CHHproviding the operator with physiologic information about thecontractile function of the LAA and stroke risk. This can be done withregional actuators positioned at the handle's terminal portion or in oneworking of the invention incorporated within a knob, collar, or rotatingsphere that is also used to deflect the desired portion of the insertedcatheter (e.g. during positioning for ablation) as depicted in FIG. 12.

Haptic rendering will enable the operator to tactually feel fineanatomic detail and subtle dynamic mechanical characteristics (e.g. theopening and closing of a patent foramen ovale). Dynamic changes intexture/softness and appreciation of inter-atrial blood flow; the timedependent changes in resistance, elasticity, motion and thickness of theinteratrial septum during the cardiac cycle; the sensation of enteringof the coronary sinus os which rotates and twists with cardiac systole,the dynamic changes in pulmonary veins and the texture of the ruggae ofthe LAA with and without cardiac arrhythmia are examples of dynamiccardiac mechanical properties that can be detected and analyzed fordiagnostic purposes.

Texture, softness, and deformation sensors at the catheter's distalportion can acquire such data. In another embodiment, textureinformation is augmented by using tissue softness sensors. These sensorscan implement catheter based vibration-based softness sensors ordeformation-based methods. The latter technique can be best realizedusing CMUT technology (Leng H and Lin Y. Development of a NovelDeformation-Based tissue Softness Sensor. IEEE Sensors Journal., Volume9, No. 5. May 2009. pp 548-554). The biomechanical characteristics ofhuman tissue relate to underlying pathology. Non-compliant vasculatureand cardiac structures are associated with various pathologic states(e.g. diastolic dysfunction and diastolic heart failure in ahypertensive patient, peripheral vascular disease). Cardiac cycledependent changes in the Young's modulus of various tissues can beobtained along with an elastodynamic assessment of tissue propertiesusing softness sensors and tactually appreciated in the CHH.

Tissue Doppler Imaging time graphs in FIG. 10 depict changes in theperiodic waveforms as the region of interest moves from a fibrillatingLAA to pulmonary vein. Once within the pulmonary vein, the fibrillatorysensation (FIG. 10 top) will change and an intermittent biphasicconstant motion will be appreciated secondary to pulmonary venous inflow(bottom). Haptic rendering serves to maintain passivity and optimize thedetection of this transition as is discussed below. The sampledwaveforms depicted are obtained with tissue and pulse wave Dopplertransesophageal recordings from sample volumes in the specified regionsof interest.

Referring to FIG. 11, conventional conductor (e.g. used in cardiacpacing leads) or carbon nanotube conductor or hybrid CNTC is connectedto the continuous film of soft PZT (PzS in figure) and directs thecurrent signal to an amplifier or preferably processor/controller, 10.When processing/haptic rendering occurs A/D conversion of the signal isrequired. An example of a soft PZT is PIC 153, a modified leadzirconate—lead titanate piezoelectric ceramics material with extremelyhigh permittivity and coupling factors, a high charge constant, and aCurie temperature of around 185.degree. C. This material is suitable forhydrophones, transducers in medical diagnostics and PZT translators.Soft PZT of the type needed (e.g. PIC 153) is manufactured by companiessuch as Physik Instrumente, Auburn, Mass. Other sensor designs andmaterials can be used and in no way is the scope and spirit of theinvention limited to a specific sensor type.

High, low and band pass filtering occur and specific components withinthe CHH tactually simulate the motion of the tissue in contact with thecatheter's distally located sensors (or EXT). One or moremicrofabricated linear and/or rotary displacement motor(s) or similaractuators are contained within the CHH. An example of such a motor isthe M-674-K High Precision Z Actuator for Bio-Automation manufactured byPhysik Instrumente, Auburn, Mass. Alternate constructs for linear androtary motors may be used as well. The motors have large torque or forceto weight ratio, high holding torque or force, high positioningresolution, short response time, low input voltage, operationindependent of the magnetic environment, and compact and gearlessdesign. Bouchiloux et al describe the design of rotary and linearultrasonic motors with free stators that are suitable for aerospace androbotic applications which can be implemented as well (InternationalCenter for Actuators and Transducers, Penn. State Univ.).

A simplified CHH accommodates one or more (preferably microfabricated)tactile feedback motor(s) comprised of a 1-DOF, linear displacement lowfrequency, LF, motor and one or more higher frequency motors, HF, withshaft and weights mounted as components within the catheter handle fortactually providing vibration/displacement information to the operator'shand (e.g. as illustrated in FIGS. 11 and 12). By way of example, (FIG.11) one or more linear displacement motors or other types of actuators,LF, which move to and fro, coaxial to the inserted catheter, driven bythe low frequency component of the current signal, I. One or more highfrequency motors, HF, imparts high frequency information forreproduction of vibrotactile information to the HH (up and down arrows).A tunable band pass filter (e.g. within processor 10) directs signalsbetween 0.33 Hz and 3 Hz to LF and signals between 3 Hz and 10 Hz to theHF. LF is designed to reproduce the normal motion of contractingmyocardium during phases of the cardiac cycle. HF reproduces pathologichigh frequency motion that occurs during arrhythmias (e.g. atrialfibrillation).

In more complex embodiments of the invention, simultaneous appreciationof multiple physiologic properties (e.g. multiple frequency information)may occur. For example, the system can relay variable vector, cardiaccycle dependent longitudinal, radial or torsional displacementinformation. In one application, the operator will have an appreciationof the resistive force upon an excimer laser or alternate extractionsystem during extraction procedures. Sensors at the distal portion of apermanently implanted lead being extracted from an atrial chamber willbe subject to vibrations from atrial arrhythmia and backward coaxialtension as a result the lead being pulled from the intracardiac tissue.If the sensor is proximate to myocardium, systolic and diastoliccontractile properties will be appreciated and force feedback willensure that the operator applies the appropriate amount of pressure atcritical time frames. Fourier transform analysis of acquired signals canbe implemented in processor 10 which delivers specific signalscharacteristic of specific anatomic regions to different actuatorswithin the CHH. These data can be saved and used for data storage (EMR)and for educational purposes.

In a simplified multidimensional mode, amplifiers receive signals fromone or more sensors and amplify and provide the signals (5 in FIG. 1) tothe HH actuators. For example, one of the three sets of PzN (e.g. FIGS.4 a and 4 c: electron micrograph image of helical carbon nanotubeconstructs, ZnOxide radial nanowire nanogenerators) is oriented alongthe longitudinal axis of the lead or catheter (z axis) and two othersets are oriented orthogonal (x, y axes) as illustrated in FIG. 4 b bythe dotted arrows. Alternate types of sensors such as triaxialfiberoptic force sensors found in catheters manufactured by Endosense SAof Geneva, Switzerland, can be used to acquire data and input toprocessor 10 and in no way are the inputs limited to piezoelectrictechnologies. More than one sensor type can be implemented and indeed,various sensors may be used that are specific to the nature of themotion data being acquired (e.g. related to bandwidth). In this example,the degree of displacement and frequency of displacement of PzN isproportionate to the action provided by the three motors within thecatheter handle. Motion is multidimensional, rotational and to and fro(coaxial). The motion (up and down arrows, y axis) is appreciated alongthe full length of the handle and is proportionate to the sensor'scurrent amplitude. The gain of the handle's motion is adjustable in alldimensions (as is the force feedback) but always proportionate tocatheter displacement/motion at its distal sensor. For optimalreproduction of tissue mechanics, omni-directionalvibration/displacement and torque of the catheter tip detected by one ormore catheter based PzNs (or other sensors) is transmitted to the handleof the catheter which can be used for positioning and manipulating theinserted catheter (virtual catheter design).

In one mode, the haptic display is a simplified version of an ordinaryhandle as known by those experienced in the art which incorporatestactile feedback mechanisms. By way of example, a collar, or triggermechanism (204 a in FIG. 12) at the end of the catheter that isconventionally used to torque/manipulate the angle of the insertedcatheter/instrument is constructed to reproduce cardiac tissue motion.This motion can be a simulation of the high and/or low frequencycomponent of tissue motion. Alternatively, the collar/trigger mechanismcan reproduce the low frequency motion and the handle body simulates thehigh frequency motion. The collar/trigger mechanism can be employed toprovide texture and temperature information and finely detailed temporalinformation (e.g. vibratory motion), as well as, a simulation of motionof the catheter's joints (e.g. torque, pitch, yaw) during deflection ofthe handle's collar(s) as this is the portion of the CHH that is incontact with the operator's fingertips.

Sensor Orientation/Frame of Reference

Navigational systems (e.g. EnSite NavX, and MNS, Niobe, Stereotaxis, St.Louis, Mo.) or satellite systems (e.g. GPS) for performing ablation asknown by those experienced in the art wirelessly detect sensororientation (e.g. via magnetic, electromagnetic field,resistive/impedance data) relative to the position of the distal portionof the catheter and essentially maintain a proper frame of reference inreal-time. Thus, intrinsic and extrinsic systems (EXT) function in asupportive fashion. This data is input to processor 10 (along withinformation regarding the CHH's position in space-time) as to maintainan accurate representation of sensor locations and CHH position in threedimensions, thereby replicating the same in the CHH in real time (doublearrows in FIG. 11). Navigational systems can be implemented along with aplurality of alternate technologies to locate catheter and the CHHposition and facilitate real time appreciation of catheter motion withthe CHH. This is communicated to the operator along with a threedimensional real-time representation of intracardiac anatomy. In apreferred embodiment, multiple sensor sites (nodes A, B, C, D) aretracked using EXT. This can be done, by way of example, using anexternally applied electrical field and measurements of impedancechanges at each node in real time or alternate methodology. Each node iscomposed of multiple sensors that reference real time position relativeto EXT and relative to other nodes along the inserted catheter. Thus,three dimensional localization occurs at multiple points along theinserted instrument and the system then provides the operator withdeterminations of motion and forces (e.g. pitch, yaw, torque) alongnodal locations. These data are input to the processor, 10, and serve togenerate tactual representation of catheter and contacted tissue motionto the HH (e.g. virtual catheter). Deployment of multiple nodes in acontiguous fashion will facilitate simulation of full length cathetermotion (distal end) in a hand held virtual catheter with similarphysical characteristics (proximal end) as illustrated in FIG. 7 a. Theoperator holds a simulated version of the catheter's distal end thatlooks and feels the same as the inserted distal end (e.g. sameelasticity/bendable joints) and while he or she manipulates the distalportion the proximal portion moves and deflects in a likewise fashionwith the same force vector and magnitude along multiple joints or nodesThe motion and forces imparted to both ends is the same (“virtual”coupling) and bi-directional communication of the catheter's and CHH'sthree dimensional position provides continuous feedback for positionframe of reference (FIG. 11—double arrows and see below). CHHlocalization can be done with positioning systems including but notlimited to satellite type GPS, thermal, electromagnetic, haptic glove,electromagnetic, resistive fields. Thus the cardiac tissue causes thehandle to move torque/bend/vibrate etc. and the operator feels this inthe CHH while the operators actions similarly affect the distal endeffectively bridging the gap caused by attenuation of intervening softtissues, catheter flexion/dampening and gross operator movement.

In one mode of the invention, intrinsic sensors are not needed for datacollection and tactile simulation is provided solely by data collectedby extrinsic means (non-invasive modalities). This is depicted in FIG. 1as input, EXT. The extrinsic methods for collecting motion data includebut are not limited to magnetic, resistive, thermal,electromagnetic/optical or impedance based navigational systems,ultrasonic/radiographic imaging. Real-time localization data output fromthree dimensional navigational systems imaging technology (e.g.intracardiac ultrasound), or alternate positioning systems (e.g.magnetic, electromagnetic, optical, impedance-based, or alternate globalpositioning system techniques) is input, IN, to the controller, 10, andused to drive the HH. Neural networks can be used to “teach” andtranslate analogous data sets between intrinsically and extrinsicallyacquired data as to facilitate the understanding of novel tactilemetrics and for optimization of system function as described herein andin the author's co-pending patent applications (Ser. No. 11/334,935).

Cardiovascular Haptic Handle—Basic System Design

Briefly, as shown in FIGS. 17 and 18, in one embodiment, a hapticcatheter system constructed in accordance with this invention includes ahandle 100 with an elongated element 102 sized and constructed so thatit can be inserted into the body of a patient to sense and probe aparticular tissue or organ. Sensors 104 are disposed either at the tipof the element 102 or at the tip and along its length as shown. Sensors104 can be internal electrodes that are used in conjunction with surfaceelectrodes placed on the patient's body along three orthogonal axes foremission of a low current, high frequency electrical field used todetermine electrical potential/field strength for electroanatomicmapping as known by those skilled in the art (e.g. EnSite NavX; St. JudeMedical, Inc., Minneapolis, Minn.). The haptic handle 100 is providedwith a plurality of mechanical controls 101 that are manipulated in aconventional manner by an operator as the element 102 is inserted intothe body to cause it or its tip and/or alternate portions to move,rotate, etc in conjunction with the sensed cardiac tissue motion. In oneembodiment, sensors 104 are at least in part located at movable pivotpoints or joints along element 102, move in unison with comparablejoints in 100 and determine forces and motion characteristics of element102 and of tissues in contact at sensor sites, 104 as described in moredetail below.

As shown in FIG. 18, signals from the sensors 104 are provided to adigital signal processor (DSP) 106 either through wires imbedded in theelement 102 or wirelessly, in which case, some preliminary signalprocessing and encoding is performed within element 102 and/or thesensor 104. The DSP 106 can be incorporated into the haptic handle, 100,or can be remote to reduce the bulk and size of the haptic handle, 100.

The DSP 106 analyzes these signals and sends control signals toactuators 108. These actuators then activate one or more tactileelements 110 to provide live, real time tactile sensations to theoperator representative of cardiac motion characteristics. The actuators108 are preferably incorporated into the body of haptic handle 100. Ifnecessary, the haptic handle 100 is made large enough so that it can beheld with two hands, with each of the hands contacting some of thetactile elements 110 whereby one hand can get tactile sensations (e.g.cardiac twist) corresponding to the signals from one set of sensors andthe other hand can get tactile sensations from the rest of the sensors.

In one embodiment of the invention, one or more external locator systems112 are used to locate the catheter and its distal end within the bodyin real time. The information from these system is used alone orcombined with information from the sensors 104 to generate the controlsignals for the actuators, 108 and in one preferred embodiment, providea three dimensional frame of reference such that the hand held handle100 is positioned appropriately in space-time during the cardiac cycle(as described below).

FIG. 19 shows another embodiment of the invention. In this embodiment,there are two separate groups of components provided, one group beingdisposed locally and the second group being disposed remotely. The localgroup includes a catheter with a handle 200, mechanical controls 201,with manipulating actuators 203 and an elongated element 202 withsensors 204. The information from the sensors 204 are fed to a localprocessor 206.

The remote components include a remote processor 306, and a remotehaptic handle 300. Within the haptic handle 300, tactile elements areprovided which are actuated by actuators (not shown). In one embodiment,the processor 206 either transmits the sensor signals to the remoteprocessor, 306, which then processes these signals and generates controlsignals for the actuators in the haptic handle, 300 and mechanicalcontrols 301. Alternatively or additionally, the sensor signals areprocessed by the local processor 206 and used to generate controlsignals which are then transmitted to the remote processor and used tocontrol the actuators. In either case, external navigational systems mayalso be used as in the previous embodiments, however they are omittedhere for the sake of clarity.

In another embodiment of the invention, depicted in FIG. 19, the haptichandle 300 is associated with either a remote, wireless connected system(302) or a detachable elongated element 302 which is a physicalsimulation of the element 202. Additional catheter actuators 305 areprovided that are also controlled by commands from processor 306 (and/or206) and in response to these commands, the actuators 306 cause theelongated member 302 to take on the shape and/or move exactly in thesame manner as the element 202. Therefore an operator can look at andfeel the member 302 and get a visual and/or tactile indication of whatis happening at and with element 202.

In yet another embodiment of the invention, depicted in FIG. 20, thehaptic handle 300 is also provided with manipulating controls 301similar to the controls 101 in FIG. 17. The operation of thesemanipulating controls is sensed within the handle 300 and movable joints304 and corresponding control signals are transmitted to the processor306 which then transmits them to the processor 206. The processor 206sends corresponding commands to another set of actuators 203 which arecoupled to mechanical controls 201 on the handle 200. In this manner, anoperator or operators can manipulate the controls 301 and 304 locallyand/or at a remote location and the actions are transmitted throughprocessors 306, 206 and actuators 203 to controls 201 thereby allowingthe operator to manipulate and operate the catheter element 202 locallyand remotely. As illustrated, sensors can be located at one or morepivot points or joints, 204 and 304, in the catheter, 202, and virtualcatheter, 302, respectively. Thus, the dynamic action of the surroundingtissues and vasculature on 202 during the cardiac cycle, and ofoperator's actions on 302 are reciprocal and sensed forces and motion at204 and 304 are coupled. Sensor 204 a and temperature texture knob,collar, ring or sphere and the like controller/actuator 304 a aredistally located on catheter 202 and handle 302, respectively andprovide highly detailed sensed information at the operator's fingertipsincluding but not limited to texture, softness, high frequency lowamplitude vibration and control of the catheter's most distal aspect.Delivery of therapies occurs at 204 b (e.g. radiofrequency ablation) iscontrolled with actuator 304 b or alternate controller and is protectedfrom sensor 204 a by an insulating mechanism and adequate distance.Communication between sensors, actuators and controllers isbidirectional. Data acquired can be stored in processing centers 400 and1000 (FIG. 1) for electronic medical record keeping, academic pursuitsand teaching purposes.

In one embodiment, three mechanical controls/lever arms, 320 (bars FIG.19), are positioned orthogonally or roughly orthogonally to one anotherabout the terminal portions of the otherwise free-floating, hand heldhaptic catheter, 302 and position 302 with the proper frame of referencerelative to the three dimensional spatial orientation of insertedcatheter 202. Position information is compared in real time withinternal sensors 204 and the handle's position sensors present in jointswith mechanical controls at 304 along with external locator system(s),112 and send signals to mechanical controls/lever arms 320 and within304 as to correctly orient 302 in space time using mechanicalcontrols/lever arms 320. The system thereby accounts for patientposition, bodily motion and even geomagnetic forces in real time.

In all the systems described above, the sensors are used to determine invivo dynamic characteristics of a specific tissue or a specific movingorgan. Dynamic characteristics include various parameters related tomotion of an immediate portion of the tissue or motion of the catheterwith respect to its surroundings, such as displacement, velocity,acceleration, oscillation amplitude, frequency, phase, etc. and theeffect of an inserted instrument on such motion.

Haptic Rendering

The limits due to sensor performance characteristics have historicallyexceeded the limits due to computation. The improved performancecharacteristics of current sensor technologies will enable hapticsynthesis to take full advantage of the currently available and emergingcomputational techniques for haptic synthesis for the manufacturing of afully transparent tactile force feedback system. For more sophisticatedversions of the invention, complex haptic rendering techniques areimplemented within processor, 10. The haptic interface is designed tofunction over a wide range of dynamic impedances. The dynamic range ofimpedances that can be rendered by the haptic system while maintainingpassivity should be large (i.e. high Z width) as to optimize the virtualexperience (see below). Impedance in this context is defined as adynamic relationship between velocity and force (Otaduy M A. HapticRendering; Foundations, Algorithms and Applications. A. K. Peters Ltd.2008). Passivity design is necessary in order to combine acontinuous-time mechanical system with a discrete time controller. Thiscan be best understood in its application to passive rendering of a onedegree of freedom haptic interface such as a virtual deformable wallsubject to perforation (e.g. interatrial septum, atrial or ventricularfree wall, vasculature obstruction) as described below. Physical andelectrical means for optimizing Z width (e.g. damping mechanisms) areapplied as needed to optimize functionality of the controller.Additionally, psychophysical techniques can act to alter the user'sperception of the impedance range of the haptic control system includingmethods of rate hardness and event-based rendering as described in thereferences provided and in more detail below.

The haptic control system is a sampled-data system subject to error whenused to monitor and simulate a dynamic process (e.g. cardiac systole).The effects of sampling can cause the system to lose passivity even withoptimal sensor and actuator design (Colgate E, Schenkel G G. Passivityof a Class of Sampled Data Systems: Application to Haptic Interfaces.Journal of Robotic Systems 14:1 (1997) 37-47). Examples of how tomaintain passivity in a sampled-data system (e.g. discrete-time controlmodel) can be found and best understood by considering an analyticalpassivity criterion for a one degree of freedom haptic interface (e.g.catheter motion opposed to a virtual deformable wall). The discrete-timecontroller model includes a unilateral constraint operator and isinclusive of A/D and D/A conversion in the feedback loop. The unilateralconstraint is a simple form of contact and collision between twoobjects. It serves well for understanding how the needed virtualenvironment applies directly to the needed haptic interface forperforming cardiac procedures (e.g. ablation of arrhythmia and cathetermanipulation). More complex models can be designed (e.g. Abbot J J,Okamura A M. Effects of Position Quantization and Sampling Rate onVirtual Wall Passivity”, IEEE Transactions on Robotics 21:5 (2005),952-964) and applied to develop the haptic systems described herein andare also discussed below (e.g. intravascular navigation).

In this invention, we will refer to a virtual deformable wall as meaningone or more cardiac or vascular structures. By way of example, thevirtual wall model will fit anatomic structures such as the interatrialand interventricular septum, myocardial tissue at various intracardiacand extracardiac locations, the ventricular free wall. These are notstatic structures and are constantly moving during normal and pathologicconditions. In one model, the system's ability to simulate the dynamicintracardiac environment is in part based on derivation andimplementation of the appropriate translation function (developed by theinventor and described in the parent and co-pending patent applications)from analogous data collected with alternate means (e.g. electromagneticthree-dimensional catheter navigational systems) and/or from other dataacquired in situ or ex vivo in the laboratory. Correlations drawn bycomparing analogous data acquired from intrinsic and extrinsic systemsenable neural networks to be applied for this purpose and serve tocalibrate the sampled data to some standard or referenced metric.Through these techniques we will better understand the physiologicrelevance of data collected with varying haptic interfaces in differentpopulations of patients.

Haptic Rendering: Haptic Interface

The type of haptic display used will depend in part on the type ofsensor used for data acquisition. This is illustrated in FIG. 13, thenetwork model of haptic simulation. The haptic interface is between thehuman operator/haptic handle and in situ cardiac tissue rather than avirtual environment which is what is conventionally understood in thefield of haptics). In this invention, coupling is not virtual as thehuman heart and vasculature follow the laws of physics and are passivesystems. This renders the total system to be completely transparent.Processing and haptic rendering techniques used to optimize theoperator's tactual experience renders the system virtual. The extentthat the system is virtual (degree of virtual coupling) is dependantupon the type of sensor(s) used, frequency of sampling, and amount ofsignal post-processing that occurs. The fundamental difference betweenthe workings of this invention and conventional haptic interfaces isthat this technology

The haptic interface (FIG. 13) can be part of an impedance or admittancedisplay depending on whether or not the system measures motion anddisplays force or measures force and displays motion. Admittance hapticdevices simulate mechanical admittance by reading force and sendingposition information. Impedance haptic devices simulate mechanicalimpedance as they read position and send force data. The latter issuitable for extrinsic sensors such as three dimensional navigationalsystems and the former for intrinsic sensors including but not limitedforce sensor technology. The workings of the invention are such thateither or both admittance and impedance displays can be used as thehaptic interface (FIGS. 14 and 15). The optimal construct will providefor a nearly passive system that has near absolute stability (as boththe operator and sampled environment are passive). That is, the virtualenvironment is a physical construct (i.e. haptic handle) rather than acomputer model as known in the gaming industry. Once haptic rendering isused in the processing of acquired data, the environment becomes virtualas the interface between the sensor and display uses digitizedinformation and data is sampled with discrete variables and is, as such,not truly passive.

In the most simplified embodiment of the invention (hybrid high/lowfrequency haptic handle), a truly passive system is present when thereis pure amplification of acquired sensor data (e.g. PzS current signals)and delivery of current directly to motors housed within the haptichandle without processing or ND conversion. For the more complex haptichandles (virtual coupling), system transparency becomes more costly.

Haptic Rendering: Destabilizing Effects of Sampling

Sampling prevents detection of the exact time when the haptic displaycontacts a dynamic tissue surface. Sensor quantitization causes a lossof information due to sensing only discrete changes in the value of theacquired signal while sampling introduces uncertainty with respect toevent timing between sampling intervals. The latter is not dependent onsampling frequency while the former is. Position sensing resolution hasthe effect of quantitizing penetration distance into the tissue surface.In one embodiment, the system purely relies on pure analog data (orduring specific time frames) and thus is passive and transparent. Thus,minimal processing will improve coupling as both cardiac tissue motioncharacteristics and human control of the catheter are passive, bound bylaws of physics. A simplified approach will reduce the full effect thatmay be realized with sophisticated haptic rendering (e.g. textureappreciation) and virtual simulations but should eliminate systeminstability.

Quantization limits the performance through velocity estimation as well.Rapidly varying velocities lead to instability. Low pass filtering theresulting velocity signal smooths out the acquired data. Filtering,however, leads to system instability secondary to increased time delayand phase distortion. Butterworth filters, which compute a velocitybased on a weighted sum of raw velocity signals and past filteredvelocity estimations, can be used to improve system stability. Heavyfiltering comes at the cost of reducing the systems ability to detectand display transient responses. In one mode of the invention, filteringintensity and characteristics can vary according to anatomic location.Location can be inferred by assessment of other data acquiredintrinsically or determined using extrinsic systems such as navigationaltechnologies. Other filtering techniques are within the scope and spiritof the invention and may be applied to prevent errors in velocitysignals (e.g. first—order adaptive window length) as described inJanabi-Sharifi F, Hayward V, Chen C J. Discrete-Time Adaptive Windowingfor Velocity Estimation. IEEE Transactions on Control Systems Technology8:6 (2000), 1003-1009.

Destabilizing errors lead to an active rather than a passive system.Virtual coupling will help improve the accuracy of the haptic display.Virtual coupling links the haptic display and virtual environment andconsists of a virtual spring and virtual damper in mechanical parallel.This enables a lack of passivity in the virtual environment whilemaintaining overall system passivity. Thus, virtual coupling renders thevirtual environment to be discrete-time passive. In the workings of thisinvention, one or more methods of virtual coupling are used to ensureoptimal passivity and to extend the passivity limit of perceived tissuestiffness (virtual stiffness) during the cardiac cycle. The virtualstiffness limit is also affected by friction and quantization interval.These introduce what is termed energy leaks into the system. A varietyof techniques may be used to limit energy leaks and provide the operatorwith the perception of a good feeling virtual environment.Psychophysical methods and passivity controllers/operators are examplesof methods to improve the haptic display.

Haptic Rendering: Psychophysical Methods—Detection of a Boundary

A rendering method for delivering a “braking pulse” upon contact with aboundary (e.g. interatrial septum) can be applied so that the force ofthe braking pulse occurs in one or more sampling period(s) (Salcudean SE, and Vlaar T D. On the Emulation of Stiff Walls and Static Frictionwith a Magneticaly Lievtated Input-Output Device. Transactions of theASME: Journal of Dynamics, Measurement and Control 119:1 (1997),127-132.97). High level damping occurs when crossing the wall boundary(e.g. interatrial septum) but is not sustained. A spring-damper virtualwall with virtual stiffness and damping can be applied and function tosimulate perceived wall stiffness and thickness which varies duringcardiac systole (e.g. increased myocardial thickness and stiffness atend-systole). Thus, by way of example, the operator can appreciate thesensation of the catheter tip fling (FIG. 16 bottom) as the cathetercourse across the interatrial septum (FIG. 16 top) while maintaining anawareness of being opposed to and then penetrating the interatrialseptum (thickness, stiffness), crossing the septum (spring) and finallybeing within the left atrial cavity (enclosure) despite cardiac cycledependent changes in tissue properties. Gathering sensor data frommultiple transeptal punctures (intrinsically acquired) simultaneouslywith extrinsic methods (radiographic, ultrasonic, electromagneticnavigational systems) will optimize system design by fine-tuning theamount of (mechanical and/or electronic) damping required anddetermining the force/duration of the braking pulse during cathetermanipulation across moving septal walls. Elimination of extraneousforces on an inserted catheter/instrument is accomplished with multiplesensors enabling system processing to subtract motion data from unwantedregions and extract the relevant tactual data.

Other methods for improving perception of contact and penetration arewithin the scope and spirit of the invention. Reproduction of the highfrequency vibration of catheter fling when crossing cardiac/vasculartissue can be achieved by gathering multiple data sets from repeatedlaboratory experiments while the operator can appreciate the sensationof contacting and penetrating cardiac tissue without attenuation in thelaboratory (i.e. with no intervening tissues between catheter handle anddistal sensors) while data is acquired as to tune the parameter of thevibration signatures (Okamura A M et al. Reality Based Models forVibration Feedback in Virtual Environments. ASME/IEEE Transactions onMechatronics. 6:3 2001 245-252.). Alternatively or additionally, thiscomparison can be made by simultaneous data analysis of intrinsicallyand extrinsically acquired data. Thus, methods for accurately modelingreality-based vibration feedback can be facilitated using experimentallyacquired data (Kuchenbecker K J. Characterizing and Controlling the HighFrequency Dynamics of Haptic Devices. PhD Thesis Stanford UniversityDepartment of Mechanical Engineering. 2006).

Haptic Rendering: Passivity Controller/Observer

Passivity controllers are another means of improving the functionalityof a sampled-data haptic system. Passivity controllers increase thenominal impedance of the haptic display by counteracting energy leaks.Passivity observers and controllers stabilize haptic interaction with avirtual environment. (Hannaford B et al. 3—Stable Control of Haptics. Intouch in Virtual Environments: Proceedings USC Workshop on HapticInterfaces, edited by Margret McLaughlin. Upper Saddle River, N.J.:Prentice Hall, 2001). Passivity observers, PO, analyze system behaviorand track the energy flow between elements to estimate errors introducedinto the sampled-data systems while passivity controllers, PC, act todissipate excess energy by adjusting the impedance between elements inthe system (e.g. injecting additional damping to dissipate energy). Thisimproves upon virtual coupling. Virtual coupling constantly moderatesthe feel of the virtual environment whereas PO/PC only do this if anenergy correction is needed. The expected non-linearity of themorphologic and physiologic features of the created intracardiac virtualenvironment (Intracardiac Tactile Exploration System described in theauthors co-pending patent application) makes exact calculation of energyflow into the virtual environment difficult. Thus, general and specificpassivity observers serve as an energy model used as an energy trackingreference. The characteristics of these energy models vary according tothe structural and frequency dependent features of the contacted tissue.Data acquired from multiple tissue samples in vivo using extrinsictechniques (e.g. ultrasonic, radiographic, optical, electromagnetic) arecompared to analogous data acquired with the haptic system's sensors(e.g. intrinsic piezoelectric nanosensors). These data are used tocompose such energy models. Thus, the translation function derived bythe correlative methods outlined in the author's co-pending patentapplications can be effectively implemented for this purpose. This willbe especially important for recreating frequency specific informationrelated to active and passive motion/deformation of real-timeintracardiac structures (e.g. interatrial septum, left atrialappendage).

In order to better understand the importance of PO/PC, consider theregion between the pulmonary veins and left atrial appendage duringatrial fibrillation (FIG. 9). The characteristic motion (e.g. frequencyand displacement information) is both highly dissipative and active injuxtaposed regions. The active region requires a PC to add damping as tomaintain stability. If the sensor is opposed to dissipative tissue alarge accumulation of positive energy in the PO is built up. Uponswitching to the active region (LAA), the PO may not act until the netenergy becomes negative, causing a delay while the accumulated excess ofpassivity is reduced. During that delay, the system can exhibit unstablebehavior. Having a PO that tracks a reference energy system (e.g. 3Dcatheter navigational system) minimizes the problem of resetting (OtaduyM A. Haptic Rendering; Foundations, Algorithms and Applications. A.K.Peters Ltd. 2008. 138-145). As mentioned above, adjustments in dampingand passivity can be made dependent on anatomic location and physiologicdata.

Other techniques or controllers for tracking and dissipating energyleaks are within the scope and spirit of the invention. For example, aport-Hamiltonian method for estimating sampled-data system errors candetermine inaccuracies caused by the use of discrete-time approximationsof a continuous system (Stramigioli et al. A novel theory for sampledata systems passivity. IEEE/RSJ International Conference on IntelligentRobots and Systems, pp 1936-1941. Washington, D.C.: IEEE ComputerSociety, 2002).

Haptic Rendering: Extending Z-Width with Damping

Physical damping in the haptic control system is of paramount importanceto counteract the energy generated from errors introduced by limitationsin operator control, sensing and discrete-time control. Maximizingsensor resolution through use of nanosensors and minimization ofsampling rate can improve performance. Physical damping mechanismsdescribed herein and elsewhere will increase the limits of virtualstiffness and virtual damping that can be passively achieved (Otaduy MA. Haptic Rendering; Foundations, Algorithms and Applications. A.K.Peters Ltd. 2008, 127-128). Viscous damping using virtual dampingtechniques in the discrete-time controller can be helpful as long as itdoes not mask the physical damping in the system. Signal processingmethods will complement mechanisms of physical damping.

Both mechanical and electrical methods of implementing high-frequencydamping serve to extend Z-width. The amount of damping required isdependent upon the frequency. More damping is needed at low frequencies.At high frequencies negative virtual damping occurs due to the phasedelay of the backwards difference differentiator used to computevelocity (Otaduy M A. Haptic Rendering; Foundations, Algorithms andApplications. A.K. Peters Ltd. 2008. 145-147). Thus, high order velocityfilters are a hindrance to obtaining optimal passivity. For example,combining “high-pass” damping and velocity filtering enables a muchhigher impedance virtual wall to be implemented passively.

The addition of a damper to the haptic interface will increase themaximum passive impedance. A mechanical viscous damper as described byColgate and Brown is one example (Colgate J E, Brown J M. FactorsAffecting the Z width of a Haptic Display. IEEE International Conferenceon Robotics and Automation. Pp 3206-3210. Washington D.C.: IEEE ComputerSociety, 1994). Again a limitation exists as the maximum passive virtualstiffness and damping are limited by the physical dissipation in themechanism. This additional physical damping can be counteracted usingdigital control and the addition of a low-passed version of generatedforce to the measured damper force. In a preferred embodiment, multipleforce sensors positioned about the inserted medical instrument helpanalyze these forces. By this method, we can mask the user's perceptionof damping at the low frequencies of human voluntary motion whileimproving the system stability and passivity at high frequencies wherediscrete-time control is ineffectual and energy leaks are mostproblematic. One method for accomplishing this is by designing analogforce sensors by motor controllers that locally monitor multiplenodes/joints along introduced catheter/sheath/lead system where catheterdeflection is controlled. This would be most important at the distalaspect of an ablation catheter for fine motor control of locations whereablative energies are delivered. Coupling stiffness and damping can bethus be controlled with multiple analog motor controllers (Kawai M, andYoshikawa T, Haptic Display of Movable Virtual Object with InerfaceDevice Capable of Continuous-Time Impedance Display by Analog Circuit.In IEEE International Conference on Robotics and Automation, pp.229-234. Washington, D.C.: IEEE Computer Society 2002). Use of extrinsicsystems (e.g. three-dimensional navigational technologies) to determinemotion characteristics and forces along multiple sites along an insertedcatheter/instrument is within the scope and spirit of the invention andin one embodiment, replaces the need for multiple intrinsic (i.e.intravascular/intra-cardiac) sensors.

Haptic Rendering: Physical and Electrical Damping

A variety of dampers may be used as described in the inventor'sco-pending patent applications. By way of example, typical physicaldampers, magnetic dampers using eddy currents, magneticorheologicaldampers and mechanical brakes can be implemented and incorporated intothe DSP and/or haptic handle. The damper implemented should have thefastest dynamic response. Analog methods for rendering continuous timebehavior can be implemented in place of or in conjunction withmechanical dampers. A controller using a resistor and capacitor inparallel with an electric motor adds frequency-dependent electricaldamping. Electric motors are gyrators and a damper on the mechanicalside of the motor acts as a resistor on the electrical side of themotor. Alternate means for effectively damping the haptic system atvarying frequencies are within the scope and spirit of the invention.These include but are not limited to electrical and physicalmethodologies.

Numerous modifications may be made to this invention without departingfrom its scope as defined in the appended claims.

The invention claimed is:
 1. A haptic system providing tactilesensations simulating the dynamic characteristics of a moving biologicalorgan or tissue of a patient comprising: a plurality of sensorsconfigured to be implanted within the patient and in contact with movingtissue or organ and generating sensor signals indicative of dynamiccharacteristics of the moving tissue or organ that intrinsically occursover a plurality of cardiac cycles; a processor receiving the sensorsignals and converting them into tactile signals; and a haptic handlehaving a plurality of tactile elements and one or more correspondingactuators coupled to said plurality of tactile elements, said actuatorsreceiving said tactile signals and, in response causing said pluralityof tactile elements to move in a manner selected to render atime-varying representation of said dynamic characteristics to the userwhen the user holds the handle.
 2. The haptic system of claim 1, whereinsaid haptic handle is capable of displacement in three dimensionsaccording to the sensor signals acquired to provide multidimensionalmotion.
 3. The haptic system of claim 2, wherein force sensor technologyis used to represent gross multidimensional motion and piezoelectricsensors are used to provide motion characteristics in fine detail. 4.The haptic system of claim 1, wherein said processor is hard wired tosaid sensor.
 5. The haptic system of claim 1, wherein said processor iscommunicating with said sensor wirelessly to receive said sensorsignals.
 6. The haptic system of claim 1, further includes a cathetercoupled to said haptic handle and having a body extending to said tissueor organ, with said sensors in contact with said tissue.
 7. The hapticsystem of claim 1, further including a localization device configured toprovide information indicating the location of the sensors.
 8. Thehaptic system of claim 7, wherein said localization device is anexternal device and includes at least one of a navigational system, anelectromagnetic system, an electrical system, magnetic system, impedancebased system, an optical system and a thermal system.
 9. The hapticsystem of claim 1, wherein said sensor is configured to sense at leastone mechanical property of a moving tissue or organ including one of atexture, temperature, elasticity, thickness, deformability andvibrotactile effects.
 10. A haptic handle system providing tactilerendering of the dynamic characteristics of a cardiac tissue comprising:a catheter having a proximal portion and a distal portion for contactwith cardiac tissue; a plurality of sensors, positioned about thecatheter, configured to be selectively coupled to the cardiac tissue andgenerating sensor signals indicative of the intrinsic motion of thecardiac tissue occurring over a plurality of cardiac cycles; a processorreceiving said sensor signals and being configured to analyze saidsensor signals for various artifacts associated with said sensor signalsthat degrade the quality of information contained in said sensorsignals, said processor being further adapted to compensate for saidartifacts and generate corresponding tactile signals; a virtualcatheter, simulating the catheter, configured to be held with both handsof an operator, the virtual catheter having tactile elements fortransmission of data based on a time-varying representation of saidtactile signals to both hands of the operator such that one handpalpates the amplitude and vector of tissue motion along the proximalportion of the catheter and the other from the distal portion of thecatheter.
 11. The system of claim 10, wherein at least said virtualcatheter is disposed remotely from said plurality of sensors, saidsystem further including a communication device providing acommunication path for signals from said sensor, whereby the virtualcatheter is configured to provide virtual real time rendering of how thedistal portion is moving at varying pivot points, joints or nodes.